This invention relates to a device for wrapping a junction band or covering sticker around the abutting ends of two aligned cigarettes and one double filter interposed therebetween, in the manufacture of filter-tipped cigarettes.
The device according to the invention is of the type wherein a rotary supporting drum mounts a peripheral annular assembly of wrapping units angularly equi-spaced from each other and each comprising two cooperating wrapping members formed with opposite arcuate active surfaces, one convex surface and one concave surface, respectively, which are co-axial with and spaced from each other, and wherein each of said wrapping units is cyclically fed with an assembly formed by two aligned cigarettes and one double filter interposed therebetween and with one junction band attached thereto and to be wrapped around said filter and adjacent ends of the two cigarettes by rolling the cigarettes-and-filter assembly by means of suitable relative angular movement of both wrapping members, around the common axis of their opposite arcuate active surfaces.
A device of this type is known from the U.S. Pat. No. 3,307,561. In this known device, both cooperating wrapping members of each wrapping unit are movable, while the assembly of two cigarettes and one double interposed filter is disposed and held in a respective suitable seat on the rotary supporting drum and--upon the rolling step for wrapping it in the junction band--it is rotated around its longitudinal axis without leaving its seat or changing its relative position on the supporting drum. This known device, therefore, requires two control means for actuating the two wrapping members. Moreover, the junction band attached to the assembly of two aligned cigarettes and one interposed double filter must be initially bridged on said cigarettes-and-filter assembly and then must be bent into a U-shape around said cigarettes-and-filter assembly. This known device is of very complicated construction and is not suitable for very high rates of speed.
This invention aims to eliminate these and other drawbacks of the known devices described above, and is substantially characterized in that one of the wrapping members, preferably the one having a concave active surface, is fixedly monted in the supporting drum, while the other wrapping member, preferably the one having a convex active surface, is provided with an end portion for receiving the cigarettes-and-filter assembly with a junction band attached thereto by an end thereof, and with an end portion for delivering the cigarettes-and-filter assembly wrapped in the junction band, and is movable cyclically with respect to the fixed members, each cycle beginning from an angular position of wrapping initiation, wherein its active surface is exposed, and its receiving end moves forwardly towards the fixed wrapping member and in front thereof until it reaches an angular position wherein the wrapping operation is terminated, wherein its active surface and its delivery end portion are directed toward the active surface of the fixed wrapping member. The movable wrapping member is then moved back from the angular position of wrapping termination to the angular position of wrapping initiation. The arrangement is such that in the angular position of wrapping initiation, the movable wrapping member cooperates with feeding means and receives, at its receiving end, the cigarettes-and-filter assembly, with the junction band stretched on the active surface of said movable wrapping member, toward the delivery end thereof. Thereafter, during the angular advancing movement of the movable wrapping member, the cigarettes-and-filter assembly meets the fixed wrapping member and is rotated thereby over the active surface of the movable wrapping member from the receiving end to the delivery end thereof, whereby it is wrapped in the junction band. During the return angular movement of the movable wrapping member, its delivery end cooperates with means to pick up the cigarettes-and-filter assembly wrapped in the junction band.
The advancing angular movement of the movable wrapping member from its wrapping initiation position to its wrapping termination position, and the successive angular return movement of said movable wrapping member from its wrapping termination position to is wrapping initiation position can occur either in opposed directions or in the same direction, i.e., the movable wrapping member can effect either a rotary reciprocating movement or a rotary unidirectional movement.
With respect to the known status of the art constituted by the U.S. Pat. No. 3,307,561, the device according to the invention has the advantage of a simpler construction, in that it requires the actuation of only one of the wrapping members of each wrapping unit on the rotary supporting drum. Moreover, the junction band is not to be straddled on the cigarettes-and-filter assembly with interposed double filter, but it is attached to said assembly by one of its ends and is then stretched over the active surface of the movable wrapping member. Since this junction band is wrapped around the cigarettes-and-filter assembly by a simple rotation of said cigarettes-and-filter assembly in a single direction over the surface of the movable wrapping member by the action of the active surface of the corresponding fixed wrapping member, it will be thus possible to attain very high operating speed rates together with a great precision of rotation.